Art of producing relief-plates for press-printing by the method known as photo-engraving.



UNITED JOSEPH W. WILI JIS, OF NEW YORK, N. Y.,

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ASSIGNOR OF ONE-HALF TO ALEXANDER BLUMENAUER, OF JERSEY CITY, NEW JERSEY.

ART OF PRODUCING- RELIEF-PLATES FOR PRESS-PRINTING- BY THE METHOD KNOWN AS PHOTO-ENGRAVING.

To all whom it may concern:

Be it known that I, JosErI-r W. WILLIS, a citizen of the United States, and resident of the city, county, and State of New York, have invented a new and useful Improvement in the Art of Producing llelietPlates for Press-Printing by the Method Known as Photo-Engraving, of which the following is a full description.

There may be a number of metals to which my method of treatment may be applied of which I am ignorant at present, however, the two metals with "which I am acquainted and in which I have Worked are copper and zinc. the finest work, such as reproductions of half tones or mezzotints almost exclusively. The

zinc plate, however, is at present used in low I grades of half tone reproductions, also almost entirely for making what is generally known as line work on zinc.

I will describe my method of treating a zinc plate, whereby I am able to reproduce from a drawing, painting, photograph or object a photo engraving on zinc plate, quite equal to the best work now accomplished on a copper plate.

My method is as follows: I take a zinc plate as usually prepared for the purpose, and coat it with a sensitized enamel, which is well known in the trade, and which responds to the action of rays of light. I place on this enamel a negative, which is made by methods well known to the trade, then place both in a suitable printing frame in the usual way, so as to be held in contact with the negative; this is then exposed to the light. The light acting upon the sensitized enamel will harden those parts exposed thereto. I then remove the plate from the frame, wash it, to remove the enamel from all parts that have not been struck by the light. I then heat theplate until enamel has hardened sufiiciently, in the judgment of the Workman. enamel a resistant to the action of acids. The plate is then ready for etching or treatment with acid. This is done by placing plate in receptacle containing nitric acid and Specification oi Letters Patent.

Application filed March 2, 1908.

Copper is used so far as I know, for.

This makes the Patented April 20, 1909.

Serial No. 418,915.

water in proportion of about one per cent. of

nitric acid to fifteen per cent. of water, though with careful stronger acid may accomplish the purpose more or less well. This operation may be repeated in the discretion of the workman, until the late is etched or cut away by the action of t e acid to a SUIIlClGl'lt depth which is generally about 1/64 of an inch. The plate is then subjected to treatment locally with perchlorid of iron which is carefully done until a facsimile of the original is reduced. l /hile performing the work of loca ly touching up the plate with the perchlorid of iron, the remaining portions may be covered or stopped out in any suitable way. A print from this plate will be quite equal to the best work of hoto engraving on co per.

g A wea acid which will do t e work will have the same effect as the dilute nitric acid. It must not be strong enough to cut away too rapidly, the object being to enable the workman to remove the plate from the bath from time to time to ascertain its condition and repeat the bath or stop it when in his judgment it has been etched sufficiently for touching up with perchlorid of iron to produce the facsimile.

That I claim and desire, to secure by Letters Patent is:

The method of producing relief plates for printing which consists in first coating a zinc plate with a sensitized enamel, then placing over it a negative or picture, then subjecting it to the action of rays of light, then washing the plate and heating it to harden the parts aflectedby the light, then subjecting it to a bath of dilute acid and then treating it locally with perchlorid of iron.

In testimony whereof, I, the said JOSEPH W. WILLIS have signed my name to this specification in the presence of two subscribing witnesses, this 29th day of February,

manipulation a weaker or 

